There were many ways, you could either go and try to illegally pass across the border and hope not to get killed, or you could get fake documents and pass through legally. Corruption was also a good thing because many people were corrupted and could get you across the border. Before the wall was built however, the best way might be to go to Berlin and cross to the part of the town that was American and then they could get you out with an airplane because they had planes come and go all the time.